MitochondrialND1Variants in 1281 Chinese Subjects With Leber's Hereditary Optic Neuropathy

Abstract

PURPOSE. The purpose of this study was to investigate the mutational incidence and spectrum of mitochondrial ND1 gene in subjects with Leber's hereditary optic neuropathy (LHON). METHODS.A cohort of 1281 Han Chinese probands and 478 control subjects underwent sequence analysis of mitochondrial (mt)DNA. Resultant variants were evaluated for evolutionary conservation, allelic frequencies, and structural and functional consequences. Respiratory complex activities were measured using lymphoblastoid cell lines derived from 25 probands carrying the mtDNA mutation and 3 controls.RESULTS. Mutational analysis identified 178 (70 missense and 108 silent) variants in the MT-ND1 gene. The incidences of known m.3460G>A, m.3635G>A, m.3733G>A, m.3866T>C, and m.3394T>C mutations were 1.33%, 0.86%, 0.08%, 0.55%, and 2.97%, respectively. Fifteen novel putative mutations were identified in 27 probands, translated into 2.1% cases of this cohort. The activity of complex I in mutant cell lines carrying one of putative mutations ranged from 66% to 76% of the average values in control cell lines, whereas activities of complexes II, III, and IV in mutant cells were comparable with those in controls. The low penetrances of optic neuropathy were observed in pedigrees carrying novel putative mutation(s). Moreover, mtDNAs in 101 probands carrying the MT-ND1 mutation(s) were widely dispersed among 15 Eastern Asian haplogroups. In particular, the occurrences of haplogroups M, M9, and M10 in patients carrying the ND1 mutations were higher than those in controls.CONCLUSIONS. These data demonstrated that the MT-ND1 gene is a hot spot for mutations associated with LHON. Our findings may provide valuable information for pathophysiology, management, and genetic counseling of LHON.Keywords: Leber's hereditary optic neuropathy, mitochondrial DNA, mutation, spectrum, ND1 gene L eber's hereditary optic neuropathy (LHON) is the most common mitochondrial disorder leading to severe visual impairment or even blindness by death of retinal ganglion cells, affecting children through adults. [1][2][3][4][5] In the majority of cases worldwide, LHON is due to one of three point mutations in the mitochondrial DNA (mtDNA) encoding three subunits of respiratory chain complex I (Nicotinamide adenine dinucleotide [NADH] dehydrogenase): m.3460G>A(MT-ND1), m.11778G>A(MT-ND4), and m.14484T>C(MT-ND6).5-10 These LHON-associated mtDNA mutations occurred in heteroplasmy (mixture of wild-type and mutated molecules) or homoplasmy (only mutated molecules). These three mutations account for approximately 90% of LHON pedigrees in some countries, whereas these mutations are only responsible for 38.3% and 46.5% cases in two large cohorts of Chinese Han subjects with LHON. 11,12 In particular, the incidences of the m.3460G>A mutation in two large cohorts of Chinese Han subjects with LHON and 159 Caucasian pedigrees with LHON were 0.44%, 2.11%, and 13%, respectively, 10-12 suggesting the variable incidence and spectrum of mtDNA mutations among the different ethnic origins.12-14 The ...

Mutation analysis of Leber's hereditary optic neuropathy using a multi‑gene panel

“…Mutations of the multi-gene panel were designed from the Mitomap database, previous reports and our previous study in a Chinese Han population (8)(9)(10). Twenty-seven amplicons, the specific primers for the point mutations, covered those of 46 mutations, as well as other substitutions in the amplicons, such as pathogenic mutations, m.3697G>A, m.10197G>A and m.14459G>A in the fragments of amplicon 4, 13 and 23, respectively.…”

“…A total of 275 unrelated LHON samples and 281 Chinese control samples were enrolled from the ophthalmology clinics at Zhejiang University School of Medicine (Hangzhou, China) and Wenzhou Medical College (Wenzhou, China) between 2004 and 2015, as described previously (8)(9)(10)12), under protocols approved by Zhejiang University and Wenzhou Medical University Ethics Committees. DNA was extracted from 1 ml peripheral blood using a QIAamp DNA Blood Minikit (51106; Qiagen China Co., Ltd., Shanghai, China).…”

“…Multi-gene target sequencing was performed using the VariantPro™ Capture Technology by LC Sciences (Hangzhou, China) as described previously (13). The 46 LHON-associated mutations were selected from Mitomap and previous studies (8)(9)(10). As presented in Table I, they Library preparation and sequencing.…”

“…The three most causative mutations, m.11778G>A (M T-ND4), m.14484T>C (M T-ND6) and m.3460G>A (MT-ND1), have been reported to account for 90% of LHON patients in a Caucasian population, but for only 38.3 and 46.5% of cases in two large cohorts of Chinese Han subjects with LHON (7)(8)(9)(10). Our previous studies have shown the spectrum of genes, MT-ND1, MT-ND4 and MT-ND6, and the frequency of the three primary mutations in a Chinese LHON population (8-10) using Sanger sequencing.…”

Biochemical evidence for a mitochondrial genetic modifier in the phenotypic manifestation of Leber’s hereditary optic neuropathy-associated mitochondrial DNA mutation

“…In this study, we investigated the pathophysiology of secondary ND6 m.14502T > C mutation in the LHON expression by taking advantage of a large cohort of 1281 Chinese probands with LHON (12,23,24,25). In this cohort, 438 individuals harboured the m.11778G > A (p.340R > H) mutation and 40 Chinese probands carried the ND6 14502T > C (p.58I > V) mutation (23,24,(26)(27)(28).…”